The response time from an impact to initial air bag deployment is extremely important for minimizing injury to one or more occupants in a vehicle which is involved in a collision. Every microsecond or millisecond saved between impact and deployment of a vehicle's air bag will substantially reduce injury in the event of an accident. As such a fast and effective air bag deployment trigger within the vehicle is essential.
Past air bag triggering devices have utilized a mechanical safing sensor also known as an inertial ball. These sensors typically include a ball and magnet arrangement in which an impact causes the separation of the ball from the magnet which in turn makes contact with two electrodes and triggers a sensor circuit leading to activation of an air bag deployment system in the vehicle. Air bag deployment is dependent upon the response time speed of its sensor and triggering device. The conventional safing sensors or mechanical triggering devices for air bag deployment have a relatively slow response time. Additionally, if more than one safing sensor or mechanical triggering device is disposed within a vehicle, all the air bags within vehicle will be deployed simultaneously. Furthermore, the ball and magnet system is large and bulky and its size prevents its placement in certain areas of a vehicle such as within a bumper. Also, the ball and magnet triggering system must be strategically placed within the vehicle in order to achieve the appropriate response upon impact. The ball and magnet triggering system may also be ineffective in certain circumstances since the ball and magnet may sometimes dislodge inappropriately thereby rendering the device prone to false deployments. For example, under some conditions, mechanical sensors may be prone to trigger by, among other things, driving over bumpy roads, banging on the vehicle, or upon slight impacts and incidental bumps directed upon the vehicle but which are below a threshold required for air bag deployment. As a result of false deployments, a vehicle owner would be forced to expend money to repack the falsely deployed air bag or to have a new one installed.
A system has recently been proposed in U.S. Pat. No. 5,335,749 to Taguchi et al. which provides an air bag triggering device having a flexible fiber optic rod arranged inside a cylindrical beam positioned within the space inside the side door of an automobile. A flexible material is also arranged inside the cylindrical beam which occupies the space between the cylindrical beam and the fiber optic. The fiber optic is connected to a light receiving portion on one end of the cylindrical beam and to a light emitting portion on the other end. In this construction, a lateral impact force to the side of the door causes a lateral deformity in the fiber optic which results in a difference in the amount of light received at the light receiving end, generally a reduced amount of light. As a result of the deformity of the fiber optic and the reduced receipt of light by the receiving end, the air bag trigger is activated resulting in inflation of the vehicle's air bag.
However, the flexible nature of the fiber optic may cause false activation of the trigger which would result in false deployment of the air bag. For example, random changes in the amount of light received at the light receiving end of a flexible fiber may cause air bag deployment. Other events such as a minor indentations in the vehicle door caused by a person leaning against the door, or driving the vehicle over a bumpy road may cause a deformity or shift the fiber optic hence causing a change in the light received by the light receiving end and causing the air bag to be falsely deployed.
Accordingly, there is a need for an air bag triggering device which is relatively compact for placement anywhere within a vehicle, which decreases deployment time for inflation of an air bag upon impact, which can be placed in a particular critical crash zone of a vehicle, and which eliminates the prevalence of false deployments inherent in the prior art.